The Design And Implementation Of A Power Efficient Wireless VoIP Terminal System

With the fast development of embedded systems, functions of embedded processors are getting more and more powerful. Therefore, to prolong the battery life has become one of the essential goals. Compared with a longer development cycle of hardware design, life cycle of software design is more flexible; furthermore, with the development of optimization in compiler and DPM (Dynamic Power Management), DVFS (Dynamic Voltage and Frequency Scaling) technology, software optimization has become an important approach to optimize power consumption.On the other hand, for most wireless embedded system such as VoIP, which consist of multiple components including MCU (Micro Central Unit), network communication module, LCD, and storage systems. Simply using hot spot code optimization or DVFS technology can only optimize power consumption of MCU. Also, simply using DPM technology can only lower power consumption of other I/O components. Moreover, experiments showed that simply using MCU focused DVFS method may increase power consumption of other I/O components and the whole system. Unlike some of the multi-media handheld devices, for a handheld wireless VoIP device, an RF (Radio Frequency) module may consume up to 40% power of the whole system. From the whole system point of view, optimization is very limited with a single DVFS optimized MCU.Purpose of this paper is to design and implement a DVFS method for a wireless audio system. According to the working mode of RF module, design a scheduling method to balance between power optimization between MCU and RF module. This paper employed two approaches to optimize power consumption of the whole system. At first, we based on a LaEDF algorithm to calculate scheduling strategy to meet requirements of voice communication and RF module working states. Second, this system selected certain frequency band to decrease transmit ion time and lower the RF module power consumption. As a wireless real-time communication product, this system is working on ISM (Industry Science and Medicine) to communicate with other devices. So how to coexisting with other wireless systems such as Bluetooth and WLAN (Wireless Local Area Network) must be taken into consideration. In this paper, we analyzed the working mode of WLAN and utilized a WLAN-Weighted FAP (Frequency Agility Protocol) algorithm to deal with the conflict; at the same time, by analyzing frequency hopping of Bluetooth, this system using different frequencies to coexisting with Bluetooth devices.In the last session of this paper, we implemented above optimizations onto a wireless handheld VoIP (Voice over Internet Protocol) terminal based on nRF2401 platform.